Bis (hydroxyphenyl) alkanes



Patented July 18, 1950 BIS HYDROXYPHENYL) ALKANES Donald R. Stevens, Wilkinsburg, and Arthur C.

Dubbs, Springdale, Pa., asslgnors to Gull Research & Development Company, Pittsburgh, Pa., a corporation of Delaware No Drawing,

Application December 22, 1947, Serial No. 793,314

3 Claims. (Cl. 260-619) This invention relates to addition agents for oils and more particularly it relates to new compounds represented by the following structural formula:

B, in.

wherein R1 is a substituent selected from the class consisting of secondary butyl and tertiary butyl groups and R2 is a substituent selected from the class consisting of alkyl, cycloalkyl, aryl, aralkyl, and alkaryi groups, and wherein said alkyl group contains at least 3 carbon atoms.

We have discovered that by condensing 2 moles of either o-secondary-butyl-paracresol or o-ter- 2 tiary-butyl-paracresol and 1 mole of an aldehyde containing at least 4 carbon atoms in the presence of a condensation catalyst such as an hydrous zinc chloride, we can produce compounds represented by the structural formula:

I: on

n R 41 R:

(13H; (EH:

wherein R1 is a substituent selected from the class consisting of secondary butyl and tertiary butyl groups and R2 is a substituent selected from the class consisting of alkyl, cycloalkyl, aryl, aralkyl, and alkai'yl groups, and wherein said alkyl group contains at least 3 carbon atoms. As examples of compounds falling within this class may be included 1,1-bisi2-hydroxy- 3-t-butyl-5-methylphenyl) butane; 1,1-bis(2-hydroxy-3-t-butyl-5-methylphenyl) isobutane; bis- (2 hydroxy 3-t-butyl-5-methylphenyl)phenylmethane; bis(2 hydroxy 3 t-butyl-5-methylphenyl) -4'-methylphenylmethane; l,1-bis(2-hydroxy 3 t-butyl-5-methylphenyl) -2-phenylethane; 1,1 bis(2 hydroxy 3-s'ec-butyl-5-methylphenyDbutane; 1,1-bis(2-hyroxy-3-sec-butyl-5- methylphenyl) isobutane; bis(2 hydroxy 3-secbutyI-E-methylphenyl) phenylmethane; bis (2-hydroxy .3 sec-butyl-5-xnethylphenyl) -4' -methylphenylmethane; 1,1 bis(2 -hydroxy-3-sec-butyl- 5-methylphenyl)-2-phenylethane; and the like. We have found that compounds of the above type'possess very good antioxidant properties,

are soluble in oil, and are insoluble in water and in dilute aqueous alkali solutions. This combination of properties makes the compounds of our invention particularly valuable for use as antioxidants in stabilizing various organic substances such as motor fuels, lubricating oils, turbine oils,

transformer oils, and the like, when added thereto in relatively small amounts. Their insolubility in water makes them particularly advantageous for stabilizing gasolines and oils which, either in storage or in treatment, come in contact with water. Their insolubility in dilute aqueous alkali solutions permits their addition to gasolines prior to the usual alkali washing step encountered in a refining operation.

We have found that the addition of from about 0.005 to about 2 per cent by weight of compounds represented by the following structural formula:

wherein R1 is a substituent selected from the class consisting of secondary butyl and tertiary butyl groups and-Ra is a substituent selected from the class consisting of alkyl, cycloalkyl, aryl, aralkyl, and alkaryl groups, wherein said alkyl group contains at least 3 carbon atoms to an oil normally tending to undergo oxidatlonal changes will substantially inhibit or greatly retard the formation of compounds which are corrosive to metals, such as bearing metals, and will increase the oxygen and gum stability of gasolines and other motor fuels. The exact amount of the compound used in any particular case will depend upon the nature of the base oil as well as the severity of the conditions to which it is subjected and also upon the particular compound chosen; in any case a small amount, suflicient to inhibit the oxidational changes normally tending to occur, is used.

In addition to a, compound of the type disclosed herein, we may incorporate other "additive agents in a lubricating oil including oiliness and extreme pressure agents, such as aromatic chlorine compounds, stabilized chlorinated parafiins, sulfurized fatty oils, and high molecular weight ketones and esters; viscosity index improvers, such as high molecular weight polymers of isobutylene and the polymers of methacrylic esters; pour point depressants, such as a condensation product of chlorinated wax and naphthalene and a condensation product of chlorinated wax and phenol followed by further condensation of this reaction product with organic acids; detergents, such as nickel naphthenate, metal salts of ethyl salicylate, and metal salts of alkyl substituted phenol sulfides; foam inhibitors, such as organesilicon oxide condensation products, organosilicol condensation products,-and organs-germanium oxide condensation products; and other oxidation inhibitors, such as alkylated phenols, if desired.

The new compounds of our invention may be prepared by condensing either o-tertiary-butylparacresol, or o-secondary-butyl-paracresol and an aliphatic or an aromatic aldehyde in the presence of a condensation catalyst. The following are examples of a few of thealdehydes which may be used in accordance with our invention: butyraldehyde, isobutyraldehyde, isovaleraldehyde, caproaldehyde, benzaldehyde, m-, and p-toluic aldehyde, phenylacetaldehyde, ethylhexaldehyde, pivalic aldehyde, a-ethyl caproaldehyde, and the like.

In carrying out the condensation reaction, the molecular ratio of the butyl paracresol compound to the aldehyde compound is advantageously maintained at about 2:1. This ratio is based upon the use of an aldehyde monomer. If an aldehyde polymer is employed, the amount of polymer used is based upon the equivalent number of moles of the monomer appearing in the polymer. For instance, if a trimer of isobutyraldehyde and o-tertiary-butyl-paracresol are condensed, the molecular ratio of the o-tertiary butyl-paracresol to the trimer of isobutyraldehyde would be about 6:1. It may further be desirable in carrying out the reaction, to dissolve the reactants in a common solvent such as glacial acetic acid. Water is formed in the course of the reaction, the reaction product separating out as a liquid or as a solid. Where the reaction product is a liquid, the product may be found in the upper layer, with the acetic acid on the bottom, or just the reverse may occur. It is therefore essential before discarding either layer to determine which layer contains the product and which layer contains the acetic acid. The product is then separated from the acid layer and washed with water and/or aqueous sodium hydroxide. This washing removes any remaining acid condensation catalyst and also any remaining acetic acid. The washed product may then be purified by recrystallization from a suitable solvent or by fractional distillation.

As condensation catalysts, we may employ sulfuric acid, phosphoric acid, anhydrous aluminum chloride, boron trifluoride, boron fluoride complexes, ferric chloride, anhydrous zinc chloride, hydrogen chloride, activated clays such as acid treated fullers earth, bentonite, floridin, and the like. The amount of the condensing agent required may be as little as 1 per cent-based on the total weight of the reactants. However, larger amounts, as high as 20 per cent by weight, may also be employed. More than about 10 per cent of the condensation catalyst is not ordinarily necessary.

The condensation reaction is carried out at a temperature below about 100 C. and advantageously at a temperature within the range of from about 0 to about 50 to 55 C. If the temperature is allowed to exceed 100 C. for-an extended period or time. undesirable side reactions may take place.

The following examples will illustrate the general method employed in preparing the compounds of our invention. These examples will also show the oxidation stability of a gasoline containing compounds of the type disclosed herein as compared to an uninhibited sample of the same gasoline. The oxidation stability test employed is known as the A. S. T. M. Standard Test, D-525-46 (Committee D-2) IDIAMPIE I 1,1 -bis (2-hydromu-3-t-butyl-5 -meth1llphenfll) iaobutane Into a flask were placed 49.3 grams (03 mole) of o-tertiary-butyl-paracresol. 10.8 grams (0.15 mole) ofisobutyraldehydeand 25 ml. of glacial acetic acid. The mixture thus formed was cooled to between about 0 and about 10 C; in an ice bath after which anhydrous hydrogen chloride was introduced slowly below the surface of the solution. The addition of hydrogen chloride was continued for three hours while maintaining the temperature of the reactants between about 0 and about 10 C. A white crystalline product which formed was washed with 5 per cent aqueous sodium hydroxide, then with water, and recrystallized from a per cent aqueous alcohol solution. The white crystals thus obtained melted at 188-189 C. and were determined to be 1,1-bis(2 hydroxy-3-tbutyl-5-methylpheny1)- isobutane.

xy Intimate Amym y butyl-e-methylphenyDisobutane 1 By diflerence.

EXAMPLE II Bis(2 hudroxy-3-t-butul-5-methulphenyl)- phenylmethane Into a flask were placed 49.3 grams (0.3 mole) of o-tertiary-butyl-paracresol, 15.9 grams (0.15 mole) of benzaldehyde, 3 grams of anhydrous zinc chloride, and 15 ml. of glacial acetic acid. The solution thus formed was cooled to between about 0 and about 10C. in an ice bath after which anhydrous hydrogen chloride was introduced slowly below the surface of the solution. The addition of hydrogen chloride was continued for one hour while maintaining the temperature of the reactants between about 0 and about 10 C. The reaction mixture was then allowed to stand until the next day (about 16 hours) during which time a solid material precipitated out of solution. The solid was separated from the liquid reaction mixture and recrystallized from 95 per cent aqueous alcohol solution. A white crystalline product having a melting point of 171-172 C. was obtained. This product was determined to be bis(2-hydroxy-3-t-butyl-5 methylphenyl) phenylmethane.

Calculated for bis- Found (z-hydroxy-ii-t Ultimate Analysis for buty --methyl Product phenyl) phenylmethane Carbon 83. 70 83. 61

Hydrogen 8. 94 8. 71

' Oxygen 7.36 7.68

1 By diflerence.

When bis(2-hydroxy-3-t-butyl 5 methylphenyl) phenylmethane. prepared as above described, was added to a reference gasoline. having an induction period of 1.6 hours, in the proportion of 0.0002 mole per 100 ml. of gasoline (0.0833 gram per 100 ml), the induction period increased to 8.6 hours.

Compounds of the classherein described were also found to be extremely satisfactory as antioxidants for turbine oils. For example, we determined the tendency of a turbine oil to oxidize in use and compared this with the tendency toward oxidation of the same oil having incor porated therein a small amount of 1,1-bis(2-hydroxy-3-t-butyl-5-methylphenyl) isobutane as the inhibitor. The tendency toward oxidation was determined by a standardized method of testing steam turbine oils, being that of Rogers 81 Miller, (Ind. Eng. Chem. 19, 308, (1927)), modified in that we controlled the supply of oxygen by metering to provide 4 liters per hour; we used a 300 ml. sample instead of a 500 gram sample, and ran the test in the presence of 60 mls. of distilled water and in the presence of metallic iron and copper. The presence of water necessitated the provision o a reflux condenser to prevent loss from volatilization. About 3 feet each of fine iron wire and fine copper wire were submerged in the 011 during the test.

In this test the deterioration of the oil due to oxidation in the presence of water, iron and copper, is measured in terms of neutralization numbers over a long period of time while the oil accelerated oxidation.

In accordance with this test, an uninhibited turbine oil having an initial neutralization number of 0.01 had a neutralization number of 0.2 after only 48 hours under accelerated oxidation. A sample of the same turbine oil having incorporated therein 0.2 per cent by weight of 1,1-bis- (2-hydroxy-3-t-butyl-5 methylphenyl) isobutanc had a neutralization number of only 0.16 even after 2000 hours.

While our invention has beendescribed above l with reference to various specific examples and embodiments, it will be understood that the invention is not limited to such illustrated examples and embodiments and may be variously practiced within the scope of the claims hereinafter made.

What we claim is:

1. A new compound having the following structural formula:

REFERENCES CITED The following references are of record in the flle of this patent:

UNITED STATES PATENTS Name Date Schoeller et a1 June 5, 1934 2,295,985 Baird et al. Sept. 15, 1942 Number 

1. A NEW COMPOUND HAVING THE FOLLOWING STRUCTURAL FORMULA: WHEREIN R1 IS A SUBSTITUENT SELECTED FROM THE CLASS CONSISTING OF SECONDARY BUTYL AND TERTIARY BUTYL GROUPS AND R2 IS A SUBSTITUENT SELECTED FROM THE CLASS CONSISTING OF ALKYL, CYCLOALKYL, ARYL, ARALKYL, AND ALKARYL GROUPS, AND WHEREIN SAID ALKYL GROUP CONTAINS AT LEAST 3 CARBON ATOMS. 